Strap stretching tool construction



y 1959 D. L. HEPLER 2,893,689

STRAP STRETCI-IING TOOL CONSTRUCTION Filed Oct. 4, 1955 3 sheets-s heet 1 If" v INVEN TOR.

Donald L.Hqp&er

ATTORNEYS;

July '7 1959 A D. L. HEPLE ,68

STRAP STRETCHING TOOL CONSTRUCTION Filed 001;, 4, 1955 3 Sheets-Sh t 2 uvwszvrox. D0mLdL.He L

BY wx' ATTORNEYS United States Patent 2,893,689 STRAP STRETCHING TOOL CONSTRUCTION Donald L. Hepler, New Bedford, Pa., assignor to Sharon Steel Corporation, Sharon, Pa., a corporation of Pennsylvania Application October 4, 1955, Serial No. 538,394 8 Claims. (Cl. 254-51) My invention relates to improvements in strap stretching tool construction and generally to a powered strap stretching tool. More specifically, my invention relates to a preferably air powered duck-bill type strap stretching tool, that is, a strap stretching tool which tightens strapping around an object being strapped by bodily forcing a seal with which the free end of the length of strapping is engaged along the supply end of said strapping.

Various prior constructions of duck-bill type strap stretching tools have been used for tensioning a length of strapping encircling an object to be strapped prior to the sealing operation, which sealing operation secures the strapping tensioned around the object. Most of these prior constructions have included a gear rack telescoped within a main frame with the gear rack being longitudinally movable in reference to the main frame. Further, a longitudinally slotted duck-bill portion is provided extending from an end of the gear rack in alignment, longitudinally of the gear rack, with a gripping dog pivoted on the main frame.

Still further, an operating handle is pivoted on the main frame and operably connected to gear means engaged with the gear rack. Finally, pawl means is operably engaged with the gear means such that upon hand reciprocation of the operating handle, the gear means will cause the gear rack to tension the strapping with the pawl means engaging a portion of the gear means and retaining the gear rack in a position so that the tension is retained on the strapping during each stroke of the operating handle. After the tensioning and sealing of the strapping, the pawl means is disengaged from the gear means to permit longitudinal movement of the gear rack so that the stretching tool may be released from the tensioned and sealed strapping.

One of the dificulties with these prior constructions of strap stretching tools is that the operating handle must be reciprocated by hand so that a considerable amount of time is required for each strap tensioning operation. Further, the amount that the strap is tensioned around the object is purely at the discretion of the person oper ating the tool so that such tension is dependent on the judgment of this operator and his physical strength in manipulating the tool.

Thus, since the tension of the strapping cannot be determined, it is possible for an operator of great strength to break the length of strapping during such tensioning operation, possibly resulting in serious injury to such operator. Further, even though the strapping does not break, it is possible to develop an excess tension therein greater than it is possible for the seal which secures the same to hold, so that it is possible during shipment of the strapped object that such over-tensioned straps may release. Finally, since the tension of the strapping cannot be determined, it is possible that the strapping may too loosely bind the object so that the strapping does not serve its intended purpose.

It is therefore a general object of the present invention 2,893,689 Patented July 7, 1959 to provide a strap stretching tool construction which overcomes and eliminates the above stated difficulties of the prior constructions.

It is a primary object of the present invention to provide a strap stretching tool construction which is automatically driven rather than hand powered.

It is a further object of the present invention to provide a strap stretching tool construction which can be adjusted to place a preset and predetermined tension on a length of strapping encircling an object.

It is still a further object of the present invention to provide a strap stretching tool construction which is preferably air powered, thereby eliminating the necessity of using complicated clutch means for securing a predetermined tensioning of a length of strapping encircling an object.

Additionally, it is an object of the present invention to provide a strap stretching tool construction which may be quickly released during the strap tensioning operation in the event of improper positioning of the length of strapping around an object or for other emergencies.

It is another object of the present invention to provide a strap stretching tool construction which includes a mechanism transmitting force between a drive motor and a rack movable longitudinally to accomplish the strap tensioning operation, which mechanism advantageously uses the force of the tensioned strapping to aid in disengagement of such mechanism from the rack in the event emergency disengagement and release of the strapping is required.

Finally, it is an object of the present invention to provide a strap stretching tool construction which accomplishes all of the above objects but yet is relatively simple in construction and economical to manufacture.

These and other objects are accomplished by the parts, constructions, arrangements, combinations and subcombinations comprising the present invention, the nature of which is set forth in the following general statement, a

preferred embodiment of which-illustrative of the'best mode of which applicant has contemplated applying the principles-is set forth in the following description and illustrated in the accompanying drawings, and which is particularly and distinctly pointed out and set forth in the appended claims forming a part hereof.

In general terms, the improved strap stretching tool construction may be stated as including a main frame member and a gear rack telescoped within the main frame member and longitudinally movable in reference to said member. The gear rack preferably is provided with duckbill means mounted at one end thereof and stop means mounted at the other end thereof. The duck-bill means preferably projects laterally from the gear rack and is longitudinally slotted, while the stop means projects from the gear rack in alignment with a portion of the main frame longitudinally of the gear rack for limiting longitudinal movement of the gear rack in a direction moving the duck-bill means away from the main frame.

The strap stretching tool construction further includes motor means, preferably an air motor mounted on themain frame, and gear means journalled in the main frame operably connected to the motor means and preferably selectively operably engageable with the gear rack to move the gear rack longitudinally of the main frame in a direction moving the gear rack duck-bill means away from the main frame. Additionally, pivotal gripping dog means is mounted on the main frame in alignment with the gear rack duck-bill means longitudinally of the gear rack, and cam means is pivoted in the main frame in association with the gear means for selectively engaging the gear means with the gear rack.

The gear means preferably includes a main shaft journalled in the main frame and operably connected to the motor means and having at least one drive gear mounted rotatable therewith, pivot frame means journalled on the main shaft, and an idlergear journalled on the pivot frame engaged with said one drive gear and selectively engageable" with the gear rack. Additionally, spring means is provided engaged with the gear means pivot frame urging the pivot frame to pivot to a position in whichthe idler gear is disengaged from the gear rack, andthe cam means is provided with spring means urging the cam means to a position to cause the pivot frame to move the idler gear into engagement with the gear rack. Finally, the pivot frame is' preferably positioned at an acute angle to the gear rack in reference to the duck-bill means end of the gear rack when the pivot frame is in a position with the idler gear engaged with the gear rack. A

Thus, the cam means will normally urge the pivot frame to a position in which the idler gear is engaged with the gear rack transmitting power from the motor means to the gear rack. If, however, during a strap tensioning operation, if the cam means is pivoted such that it does not urge the pivot frame to a position engaging the idler gear with the gear rack, any forces on the gear rack urging the gear rack longitudinally in a direction moving the duck-bill means toward the main frame, will urge the pivot frame to pivot to a position in which the idler gear is disengaged from the gear rack.

By way of example, an embodiment of the strap stretching tool construction of the present invention is illustrated in the accompanying drawings forming a part hereof, wherein like numerals indicate similar parts throughout the several views and in which:

Fig. 1 is a side elevation of the strap stretching tool operably engaged with a length of strapping and a seal; Fig. 2, an end view of the strap stretching tool of Fig. 1;

' Fig. 3, a fragmentary top plan view looking in the direction and at the location of the arrows 33 in Fig. 1;

4, a sectional view, part in elevation, looking in the direction of the arrows 4-4 in Fig. 1;

Fig. 5, a sectional view, part in elevation, looking in the direction of the arrows 55 in Fig. 1;

' Fig. 6, a fragmentary vertical section, part in elevation, looking in the direction of the arrows 66 in Fig. 4;

Fig. 7, a fragmentary vertical section, part in elevation, looking in the direction of the arrows 77 in Fi Fig. 8, a fragmentary vertical section, part in elevation, looking in the direction of the arrows 88 in Fig. 4 and showing the pivot frame means in a position in which the idler gear is engaged with the gear rack;

Fig. 9,, a view similar to Fig. 8, but with the pivot frame means in a position in which the idler gear is disengaged from the gear rack; and V Fig. 10, a sectional view, part in elevation, looking in the direction of the arrows 10-40 in Fig. 8.

The strap stretching tool construction comprising the present invention includes a main frame, generally indicated at 20, a gear rack, generally indicated at 21, and a drive motor, generally indicated at 22. The drive motor 22 is preferably an air motor of standard construction and being provided with the throttle pin 23, a pivotal throttle lever 24 and a throttle lever spring clip 25. Throttle pin 23, throttle lever 24 and throttle clip 25 are mounted positioned such that pivotal movement of the throttle lever 24 toward the motor 22 depresses the throttle pin 23 supplying air to the air motor, and full pivotal movement of throttle lever 24 toward the air motor causes the throttle clip 25 to engage over lever 24 and retain it holding the pin 23 depressed or the air motor on.

Throttle pin 23 projects laterally from the. side of case. 26 of drive motor 22 spaced from the outer end of'said case, and throttle lever 24,55 pivotally mounted at the outer end of case 26 extending generally longitudinally of the case past throttle pin 23. Throttle clip 7 main frame 29 and extending therefrom preferably by means of the threaded connection 27, as shown in Fig. 6. Drive shaft 28 of .drive motor 22 is connected to a worm 29 journalled in the main frame 20 and worm 29 is operably engaged with a worm gear 30.

As best seen in Figs. 4, 6 and 10, worm gear 30 is mounted on a main shaft 31 journalled in the main frame 20 and is fixed thereon for rotation therewith, so that rotation of the drive shaft 28 of drive motor 22 rotates worm 29, worm gear 30 and ultimately, main shaft 31. Drive gear 32 is also mounted on main shaft 31 for rotation therewith and spaced from worm gear 30, and the pivot frames 33 and 34 are journal-led on main shaft 31 adjacent either side of drive gear 32, as shown. As seen in Figs. 5, 8 and 9, idler gear 35 is journalled on and between pivot frames 33 and 34- in operable engagement with drive gear 32, so that idler gear 35 will be rotated upon rotation of drive gear 32, but is rotatable around drive gear 32 and main shaft 31 within the confines of main frame 20, due to the pivotal connection ofpivot frames 33 and 34 with main shaft 31.

Gear rack 21 is received telescopically and extending longitudinally through the lower portion of main frame 20 in vertical alignment with and underlying drive gear 32 and idler gear 35. Further, gear rack 21 is provided over a portion of its longitudinal length with the spaced vertically upwardly extending drive teeth 36, so that pivotal movement of the frames 33 and 34 toward gear rack 21 brings idler gear 35 into engagement with drive teeth 36. Thus, rotation of main shaft 31 by drive motor 22, as before described, rotates drive gear 32 and idler gear 35, and upon engagement of idler gear 35 with the gear rack drive teeth 36, idler gear 35 will move gear rack 21 longitudinally through and in reference to the main frame 20.

As best seen in Figs. 1 and 3, gear rack 21 is provided with a duck-bill seal-abutting portion 37 and a stop pin 38. Duck-bill portion 37 is mounted at the end of gear rack 21 spaced from the forward end 39 of main frame 20 and stop pin 38 is preferably mounted extending downwardly spaced slightly from the end of gear rack 21 spaced from the rearward end 40 of main frame 20.

Duck-bill portion 37 extends laterally from gear rack 2-1 and is provided with a front generally vertical sealabutting surface 41. Further, duck-bill portion 37 is flared both upwardly and downwardly from forward surface 41 rearwardly, so that it has a generally triangular vertical cross-section. Finally, portion 37 is provided with a guide slot 42 extending longitudinally therethrough in reference to gear rack 21, and laterally adjacent gear rack 21.

Stop pin 38, as above stated, extends downwardly from the rearward end of gear rack 21 and thus, this stop pin limits the forward movement of gear rack 21 through main frame 29 by engagement with the rearward end 40 of main frame 20. Further, the drive teeth 36 of gear rack 21 are formed with an arcuate recess 43 at a point spaced rearwardly from the duck-bill portion 37 and a relief 43a is formed in gear rack 21 at the n f d i e ee h 6 paced f om op pi 38 f D I- poses to be hereinafter described.

A cam, shaft 44. is j ournalled in main frame 20 spaced upward from pivot frames 33 and 34 and generally vertically overlying idler gear 35. Cam member 45 is mounted on cam shaft 44 for rotation therewith and in vertical alignment with pivot frames 33 and 34.

Further, cam member 45 is provided with spaced cam portions 46 and 47 extending therefrom, with cam portion 46 overlying pivot frame 33 and cam portion 47 overlying pivot frame 34, so that upon limited rotation of cam shaft 44, cam member 45 will rotate engaging cam portions 46 and 47 with pivot frames 33 and 34, respectively. Cam portions 46 and 47, pivot frames 33 and 34, and idler gear 35 are arranged and dimensioned such that upon engagement of the cam portions 46 and 47 with pivot frames 33 and 34, idler gear 35 will be moved into engagement with the rack teeth 36 of gear rack 21, and upon rotation of cam member 45 such that cam portions 46 and 47 are disengaged from pivot frames 33 and 34, these pivot frames will be permitted to move into a position in which idler gear 35 is disengaged from rack teeth 36.

Cam shaft 44 has the control lever 43 mounted at one end thereof for rotation therewith and is operably connected at the other end thereof, with a spring member 49. As viewed in Figs. 8 and 9, spring member 49 urges cam shaft 44 in a counter clockwise direction, so that the normal position of cam member 45 is with cam portions 46 and 47 engaged with pivot frames 33 and 34, maintaining the idler gear 35 engaged with the rack teeth 36 of gear rack 21. Further, when cam member 45 is in this normal position, the control lever 48 extends upwardly in reference to main frame 21 as shown in full lines in Fig. 1.

A spring member 50 is mounted on main frame 29 operably engaged with pivot frames 33 and 34 through a pin 51, which pin extends between pivot frames 33 and 34 at the side of drive gear 32 opposite from idler gear 35, that is to say, pin 51 is at the opposite end of pivot frames 33 and 34 from the end of these pivot frames in which idler gear 35 is journalled, so that pin 51 is at one side of main shaft 31 and idler gear 35 is at the other side of main shaft 31. Thus, as viewed in Figs. 8 and 9, spring 50 urges pivot frames 33 and 34 to rotate about main shaft 31 in a counter clockwise direction, as opposed to the cam portions 46 and 47 of cam member 45 urging pivot frames 33 and 34 to rotate in a clockwise direction.

In view of this construction, when cam portions 46 and 47 are not engaged with pivot frames 33 and 3 4, spring 50 will urge these pivot frames to move the idler gear 35 out of engagement with rack teeth 36 of gear rack 21. Spring 49, connected to cam shaft 44 and urging cam portions 46 and 47 to engage pivot frames 33 and 34, is, however, of greater strength than spring 50, so that the normal position will be for cam portions 46 and 47 to urge idler gear 35 into engagement with rack teeth 36 in opposition to the spring 50.

One of the important features of the present invention is that pivot frames 33 and 34 extend downwardly and rearwardly from main shaft 31 toward gear rack 21, or generally in a direction toward the end of gear rack 21 opposite from the duck-bill portion 37. Thus, as viewed in Figs. 8 and 9, when cam portions 46 and 47 urge pivot frames 33 and 34 into a position in which idler gear 35 is engaged with rack teeth 36, pivot frames 33 and 34 will extend forwardly from gear rack 21, or in a direction toward the end of gear rack 21 on which duckbill portion 37 is mounted, at an acute angle, so that a force on duck-bill portion 37 tending to force the gear rack 21 longitudinally rearwardly through main frame 20, while idler gear 35 is rotated in a clockwise direction, tends to separate idler gear 35 and rack teeth 36. The advantages of this construction feature described above will be hereinafter more fully described.

A generally horizontal foot member 52 extends laterally from main frame 20 and from the forward end 39 of 7 5 main frame 20 rearwardly in alignment with duck-bill portion 37 of gear rack 21. Further, the upper surface of foot member 52 is preferably on substantially the same horizontal plane as the guide slot 42 of duckbill portion 37, so that a piece of strapping extending through guide slot 42 may extend rearwardly past the forward end of main frame 20 and rest on the top surface of foot member 52.

Gripping dog 53 is pivoted on main frame 20 above foot member 52, with the gripping surface 54 of the gripping dog engageable with the top surface of foot member 52. As viewed in Fig. 1, gripping dog 53 extends downwardly and rearwardly from its pivotal connection to main frame 23, with the gripping surface 54 being urged toward the top surface of foot member 52 by means of spring 55 bearing against gripping dog 53, as shown, and tending to rotate the gripping dog in a clockwise direction. Thus, when a piece of strapping is engaged over foot member 52 and under the gripping surface 54 of gripping dog 53, it will be retained therebetween by the force of spring member 55, and a force on the piece of strapping tending to pull it in a direction away from the forward end 39 of main frame 20, will cause gripping dog 53 to more tightly grip the strapping against the foot member 52, due to the rearwardly angular arrangement of gripping dog 53 in reference to foot member 52.

In the operation of the strap stretching tool construction comprising the present invention, as illustrated in Fig. 1, a length of strapping may be positioned around an object to be strapped, with a conventional seal 56 positioned encircling the supply end 57 of the strapping. The free end 58, after encircling the object, is then threaded through the seal beneath the supply end 57, with said free end then being doubled back beneath the seal, as shown.

The strap stretching tool, with the gear rack positioned so that the duck-bill portion 37 is substantially its minimum distance from the forward end 39 of main frame 20, is then positioned so that the seal-abutting surface 41 of duck-bill portion 37 is spaced rearwardly from the rearward end of seal 56 only a slight distance, while the free end 57 of the strapping is fed through guide slot 42 of duck-bill portion 37, and between foot member 52 and gripping dog 53, as shown. Further, at this point of the operation, the control lever 48 is in its normal position, as shown in Fig. 1, in full lines, so that cam portions 46 and 47 are engaged with pivot frames 33 and 34, and idler gear 35 is engaged with the drive teeth 36 of gear rack 21, in the position shown in Fig. 8.

Throttle lever may then be pivoted toward drive motor 22, so that throttle pin 23 is depressed admitting air to drive motor 22. lf desired, throttle lever 24 may be pivoted until the end thereof engages beneath throttle clip 25 and the drive motor 22 will remain on until throttle lever 24 is released from throttle clip 25.

Actuation of drive motor 22 rotates drive shaft 28 and worm 29, thereby rotating worm gear 33 and main shaft 31 in a counterclockwise direction, as viewed in Fig. 6. As viewed in Fig. 8, counterclockwise rotation of main shaft 31 rotates drive gear 32 counter clockwise, thereby rotating idler gear 35 clockwise and moving gear rack 21 forward or in a direction moving the duck-bill portion 37 away from the forward end 39 of main frame 20.

Since the supply end 5'7 of the length of strapping is retained stationary by the gripping dog 53 bearing against foot member 52, forward movement of duck-bill portion 37 moves seal 56 to the left, as viewed in Fig. 1, along the supply end of strapping 57, while this supply end slides through guide slot 42 of duck-bill portion 37. Further, since the free end 53 of the length of strapping is doubled beneath and thereby engaged with seal 56, movement of seal 56 carries the free end 53 also to the left, as viewed in Fig. 1, thusly contracting the length of strapping around the object being strapped.

If, as preferred, thedrive motor '22 is an air motor, the motor may be set so that this strap contracting or tension- :ing operation is continued until a predetermined tension -isdevelope'd in the strapping, at which point, the air :motor will stall. Further, with the air motor in its stalled zcondition retaining the tension on the strapping, a separate conventional sealing tool may beused to crimp seal 56 thereby securing the length of strapping around the-object being strapped. Thereafter, throttle lever24 may be released from throttle clip shutting off the drive motor 22 and the supplyend'57 of the strapping may be severed between seal '56 and-duck-bill portion 37 thusly completing-the strapping operation.

The strap stretching tool may then he prepared for the next strap tensioning operation by first removing the -=strapping retained threaded through guide slot 42 of duckbill portion 37 and beneath gripping dog 53, and then returning the gear rack 21 to a position in which the duck- :bill portion 37 is'nearest the forward'end '39 of main frame 20. The strapping is disengaged from gripping dog-53 merely by moving the strapping rearwardly in reference to the gripping dog, and since the gripping dog angles downwardly and rearwardly in reference to foot member 52,:the rearwardmovernent of the strapping will cause a "slight compression of spring 55, releasing the strapping from between gripping dog'53 and foot member 52.

Gear rack 21 may be returned to its starting position by moving control lever 43 from its position shown in full lines in Fig. l, to its position shown in dot-dash lines therein, such movement being against the pressure of spring member 4?. This rotates cam member 45 in a clockwise direction, asviewed in Figs. 8 and 9, moving the cam portions 45 and 47 from the position shown in Fig. *8, to theposition shown in Fig. 9, thereby permitting spring member 50 to urge pivot frames 33 and 34 in a counter clockwise direction and disengaging idler gear from the gear rack drive teeth 36, as shown in Fig. 9. The gear rack 21 is then free to he slid rearwardly in reference to main frame 20.

The purpose of the arcuate recess 43 formed in the drive teeth 36 of gear rack 21, as shown in Fig. 1, is for ease in reengagement of the idler gear 35 with the rack teeth 36. If desired gear rack 21 may he slid rearwardly in reference to main frame 26 until recess 43 underlies idler gear 35, and upon reengagement of cam portions 46 and 47 with pivot frames 33 and 3d, idler gear 35 will be received in recess 43, making it unnecessary to exactly match the teeth of idler gear 35 with the gear rack drive teeth 36.

If, for instance, the teeth of idler gear 35 do not mesh with gear rack drive teeth 36, pivot frames 33 and 34 will be held slightly upwardly from their maximum downward position, with cam portions 46 and 47 bearing against these pivot frames due to the pressure of spring member 49. Upon momentary actuation of drive motor 22, however, prior to positioning the strap stretching tool for the next tensioning operation, the continued downward pressure of cam portions 46 and 47 against pivot frames 33 and 34 will cause the teeth of idler gear 35 to engage with the gear rack drive teeth 36, so that the gear rack is moved a short distance longitudinally forwardly, and the idler gear 35 is engaged with gear rack drive teeth 36 rearwardly of recess 43. The strap stretching tool is then ready for the next tensioning operation.

The purpose of the relief 43:: on gear rack 21 is to prevent locking of the drive teeth 36 with the idler gear 35 in the event that gear rack 21 becomes fully extended. It is possible if relief 43a were not provided, that the idler gear 35 may wedge at the end of the drive teeth 36 toward the stop pin 38, thereby preventing disengagement of gear 35 from teeth 36, despite the position of cam portions 46 and 47 in relation to pivot frames 33 and 34. Relief 43a prevents'such locking by providing clearance for idler gear 35 beyond the last of the drive teeth 36 toward stop pin 38.

The particular before "described angular arrangement of the pivot frames 33 and 34 in reference to thegear rack 21 provides for easy disengagement of the idler gear 35 from engagement with the gear rack teeth 36, even though the strap stretching tool is retaining tension on a length of strapping. Since the tension is being retained on the strapping by the gripping dog "53 gripping one end oft-he strapping and the duck-bill portion '37 abutting a seal "56 retaining the other end -of the strapping, a force is transmitted rearwardly through duck-bill portion 37 'into gear raokfzl.

In --the event- 0f an emergency therefore, since= pivot frames 33 and34=angle upwardly at an acute angle in reference to the duck-bill portion 37 ofgear rack 21, to release the tension on the strapping it is only necessar y to depress control lever is so .that earn portions 46 and 47 are rotated permitting the pivot frames to pivot upwardly, and the rearward directed force through gear rack 21-will cause an immediate separation or disengagement of idler gear 35 from the gear rack dhiveteethBd. l hereafter, spring memberSll-willretainthe-piVotframes 35 and 34 in this upwardly pivoted positionpermitting gear rack 21 to freely slide-longitudinallyin reference to main frame 24 Thus, there is no binding between idler gear 35 and the gear rack drive teeth 35, even though a rearward force is directed through gear rack 21, but rather this rearwardly directed force aids in a fast and smooth disengagement.

As before stated, it is preferred that drive motor 2 2::is an air motor, .so that this motor can be adjusted for a predetermined stall torque, and at-the point-of suchsta'll, will retain the length of strapping properly tensioned-until the seal 56 can be crimped. T his stalling, howevencan also be provided by useo'f an hydraulic motor, orro't-her motor means may be used in conjunction with various clutchmeaus to accomplish the same purpose. Advantages, however, of simplicity, minimum space requirementssanda minimum cost of manufacture are provided by the use of an air motor.

Further, by use of a drive motor ZZhaVing-the stall feature, Whether air, hydraulic orrother motor means with clutch means, final tension of the strappingmaybepreset and an excess tension will never be developed in the strapping by the strap stretching tool. This eliminates the danger .of the strapping accidentally breaking and injuring workmen or material which has .been bound by the strapping. This feature further prevents the strapping from binding the object too loosely,=since the-drive motor 22 may be always retainedin on position until the seal 56 is crimped.

Thus, the present invention provides a strap stretching tool construction which eliminates the before discussed difficulties .of the prior constructions; which is automatically driven rather than hand powered; which can b adjusted to place a preset and predetermined tension on a length of strapping encircling an object; which is preferably :air powered, thereby eliminating the necessity of using complicated .clutch means for securing a predetermined tensioning of a length of strapping encircling an object; which may be quickly released during the strap tensioning operation in the event of improper-positioning of the length of strapping around an object orfor other emergencies; which includes mechanism transmitting force between a drive motor and a rack movable longitudinally to accomplish the strap tensioning operation, which mechanism advantageously uses the force of the teusioned strapping to aid in disengagement of such mechanism from the rack in the event emergency disengagement is required; and which provides all of the above features but yet is relatively simple in construction and economical to manufacture.

In the foregoing description, certain terms have been used for brevity, clearness and understanding, but no unnecessary limitations are to be implied therefrom, because such words are used, for descriptive purposes herein and are intended to be broadly construed.

' Moreover, the embodiment of the improved construction illustrated and described herein is by way of example and the scope of the present invention is not limited to the exact details of construction shown.

Having now described the invention, the construction, operation and use of a preferred embodimet thereof, and the advantageous new and useful results obtained thereby, the new and useful construction and reasonable mechanical equivalents thereof obvious to those skilled in the art are set forth in the appended claims.

I claim:

1. A strap stretching tool construction including a main frame member, strap tensioning means operably mounted on the main frame member for being actuated to contract and tension a length of strapping around an object to be strapped, the strap tensioning means including a rack operably mounted on the main frame member movable forwardly and rearwardly with respect to the main frame member and having gear teeth formed thereon, the rack being movable forwardly of the main frame member to tension the length of strapping, gear means, pivot means mounting the gear means on the main frame member for selective pivotal movement of said gear means toward the rack gear teeth for engagement with said rack gear teeth and for pivotal movement of said gear means at least slightly rearwardly and away from the rack gear teeth for disenggement from said rack gear teeth, means operably connected with the gear means for rotating the gear means to move the rack forwardly of the main frame member to contract the strapping when the gear means is engaged with the rack gear teeth, the tension developed in the strapping urging the rack rearwardly and thereby urging the gear means to pivot rearwardly and away from the rack, and means operably connected with the rear means for at least selectively controlling the engagement of the gear means with the rack.

2. A strap stretching tool construction including a main frame member, strap tensioning means operably mounted on the main frame member for being actuated to contract and tension 21 length of strapping around an object to be strapped, the strap tensioning means including a rack operably mounted on the main frame member movable forwardly and rearwardly with respect to the main frame member and having gear teeth formed thereon, the rack being movable forwardly of the main frame member to tension the length of strapping, a first gear means mounted on the main frame member spaced from the rack, a second gear means, pivot means mounting the second gear means on the main frame member pivotal toward and away from the rack gear teeth around the first gear means and selectively engageable with said rack gear teeth, the first and second gear means being operably connected for transmitting rotatable motion therebetween and the second gear means moving around the first gear means as the second gear means moves toward and away from the rack so that said gear means remain operably connected despite the pivotal position of the second gear means, the second gear means being positioned rearwardly of the first gear means when engaged with the rack gear teeth and being pivotal at least slightly rearwardly and away from said rack gear teeth for disengagement therefrom, means operably connected with the first gear means for rotating the first gear means to rotate the second gear means and to move the rack forwardly of the main frame member and thereby contract the strapping when the second gear means is engaged with the rack gear teeth, the tension developed in the strapping urging the rack rearwardly and thereby urging the second gear means to pivot rearwardly and away from the rack, and means for at least selectively controllingk the engagement of the second gear means with the rac 3. A strap stretching tool construction including a main frame member, strap tensioning means operably mounted on the main frame member for being actuated to contract and tension a length of strapping around an object to be strapped, the strap tensioning means including a rack operably mounted on the main frame member movable forwardly and rearwardly with respect to the main frame member and having gear teeth formed thereon, the rack being movable forwardly of the main frame member to tension the length of strapping, pivot frame means pivotally mounted on the main frame member pivotal toward and away from the rack gear teeth, gear means mounted on the pivot frame means and selectively engageable with the rack gear teeth when the pivot frame means is pivoted toward said rack gear teeth, the pivot frame means being mounted extending in a direction forwardly and away from the rack to pivot the gear means at least slightly rearwardly and away from the rack gear teeth for disengagement therefrom when the gear means is engaged with said rack gear teeth, means operably connected with the gear means for rotating the gear means to move the rack forwardly of the main frame member and contract the strapping when the gear means is engaged with the rack gear teeth, the tension developed in the strapping urging the rack rearwardly and thereby urging the gear means to pivot rearwardly and away from the rack, and means operably connected with the pivot frame means for selectively controlling the pivotal movement of the pivot frame means and thereby selectively controlling the engagement of the gear means with the rack.

4. A strap stretching tool construction including a main frame member, strap tensioning means operably mounted on the main frame member for being actuated to contract and tension a length of strapping around an object to be strapped, the strap tensioning means including a rack operably mounted on the main frame member movable forwardly and rearwardly with respect to the main frame member and having gear teeth formed thereon, the rack being movable forwardly of the main frame member to tension the length of strapping, gear means, pivot means mounting the gear means on the main frame member for selective pivotal movement of said gear means toward the rack gear teeth for engagement with said rack gear teeth and for pivotal movement of said gear means at least slightly rearwardly and away from the rack gear teeth for disengagement from said rack gear teeth, means operably connected with the gear means for rotating the gear means to move the rack forwardly of the main frame member to contract the strapping when the gear means is engaged with the rack gear teeth, the tension developed in the strapping urging the rack rearwardly and thereby urging the gear means to pivot rearwardly and away from the rack, and selectively movable cam means operably connected with the gear means for moving the gear means into engagement with the rack gear teeth and holding the gear means in engagement with said rack gear teeth.

5. A strap stretching tool construction including a main frame member, strap tensioning means operably mounted on the main frame member for being actuated to contract and tension a length of strapping around an object to be strapped, the strap tensioning means including a rack operably mounted on the main frame member movable forwardly and rearwardly with respect to the main frame member and having gear teeth formed thereon, the rack being movable forwardly of the main frame member to tension the length of strapping, a first gear means mounted on the main frame member spaced from the rack, a second gear means, pivot means mounting the second gear means on the main frame member pivotal toward and away from the rack gear teeth around the first gear means and selectively engageable with said rack gear teeth, the first and second gear means being operably connected for trans mitting rotatable motion therebetween and the second gear means moving around the first gear means as the second .gear means moves toward and away from the rack so that said gear means remain operably connected despite the pivotal position of the second gear means, the second gear means being positioned rearwardly of the first gear means when engaged with the rack gear teeth and being pivotal at least slightly rearwardly and away from said rack gear asaaese 11 teeth for disengagement therefrom, means operably connected withztheifirst :gear means for rotatingthe first gear means-to :rotatethe second gear means and to move the rack forwardly of the main frame member and thereby contract the strapping when the second gear means is engaged with :the rack gear teeth, the tension developed in the strapping urging the rack rearwardly and thereby urging the second gear means to pivot rearwardly and away from therack, and selectively movable cam means operably connected-with thesecond gear means for moving the second gear means into engagement with the rack gear teeth and holding the second gear means in engagement with saidrack gear teeth.

6. A strap stretching tool construction including a main frame member, strap tensioningmeansoperably mounted on the main frame member for being actuated to contract and tension a length .of strappingaround an object to be strapped, the strap tensioning means including a rack operably mounted on the mainframe member movable forwardly and rearwar'dly with respect to the main frame member and having gear teeth formed thereon, the rack being movable forwardly of the main frame member to tension the length of strapping, pivot frame means pivotally mounted on the main frame member pivotal toward and away from the rack gear teeth, gear means mounted on the pivot frame means andselectively .engageable with the rack gear teeth when the pivot frame means is pivoted toward said rack gear teeth, the pivotframe means being mounted extending in a direction forwardly and away from the rack to pivot the gear means at least slightly rearwardly and away from the rack gear teeth for disengagement therefrom when the gear means is engaged with said rack gear teeth, means operably connected with the gear means for rotating the gear means to move the rack forwardly of the main frame member and contract the strapping when the gear meansis engaged with the rack gear teeth, the tension developed in the strapping urging the rack rearwardly and thereby urging the gear means to pivot rearwardly and away from the rack, and selectively movable cam means mounted for abutting engagement with the pivot frame means for selectively moving the pivot frame means toward the rack to engage the gear means with the rack gear teeth and holding the pivot frame means in said position with the gear means engaged with the rack gear teeth.

7. A strap stretching tool construction including a main frame member, strap tensioning means operably mounted on the main frame member for being actuated to contract and tension a length of strapping around an object to be strapped, the strap tensioning means including a rack operably mounted on the main frame member movable forwardly and rearwardly with respect to the mainframe member and having gear teeth formed thereon, the rack being movable forwardly of the .main frame member to tension the length of strapping, gear means, pivot means I mounting the gear means on the main frame member for selective pivotal movement of said gear means toward the rack gear teeth for engagement with said rack gear teeth and for pivotal movement of said gear means at least slightly rearwardly and away from the rack gear teeth for disengagement from said rack gear teeth, means operably connected with the gear means for rotating the gear means to move the rack forwardly of the main frame member to contract the strapping when the gear means is engaged withthe rack gear teeth, the tension developed in the strapping urging the rack rearwardly and thereby urging'theigearmeans to pivot rearwardly and awayfrom the rack, selectively movable cam means :operably connected with .the' gear means :for moving the gear means into engagement with therack gear teeth and holding .the gear means in engagement with said rack gear teeth, first resilient means operably connected to the cam meansnrging the cam means to move the gear means into engagement with therack gear teeth and hold the gear means in engagementwith said rack gear teeth, second resilient means operably connected to the gear means urging the gear means to pivot away from engagement with the rack gear teeth, and the holding force of said cam means with the first resilient means being greater than the resilient force of said second resilient means.

8. A strap stretching tool construction including amain frame member, strap tensioning meansoperably mounted on the mainframe member for being actuated to contract and tension a length of strapping around an object to be strapped, the strap tensioning means including a rack operably mounted on the main frame member movable forwardly and rearwardly with respect to the main frame member and having gear teeth formed thereon, the rack being movable forwardly of the main frame member to tension the length of strapping, pivot frame means pivotally mounted on'the main frame member pivotal toward and away from the rack gear teeth, gear means mounted on the-pivot'frame means and selectively engageable with the rack gear-teeth when the pivot frame means is pivoted toward said rack gear teeth, the pivot frame means being mounted extending in a direction forwardly and away from the rack to pivot the gear means at least slightly 'rearwardly and away from the rack gearteeth for disengagement therefrom when the gear means is engaged with said rack gear teeth, means operably connected with the gear means for rotating the gear means to move the rack forwardly of the main frame member and contract the strapping when the gear means is engaged with the rack gear teeth, the tension developed in the strapping urging the rack rearwardly and thereby urging the gear means to pivot rear-wardly and away from the rack, selectively movable cam means mounted for abutting engagement with .the pivot frame means for selectively moving the pivot frame means toward the rack to engage the gear means with the rack gear teeth and holding the pivot frame means in said position with the gear means engaged with the rack gear teeth, first resilient means operably connected to the cam means urging the .cam means to move the pivot frame means to its position in which the gear means is engaged with the rack gear teeth and in which the gear means is held in engagement with said rack gear teeth, second resilient means operably connected to :the pivot frame means urging the pivot framemeans to .pivot away from its position in which the gear means is engaged with the rack gear teeth, and the-holding force of said cam means with the first resilient means being greater than the resilient force of said second resilient means.

References-Cited in the file of this patent UNITED STATES PATENTS 1,885,742 Mac Chesneyet al. Nov. 1, 1932 2,007,002 Porter Aug. 18, 1935 2,204,572 Childress June 18, 1940 2,525,422 Nast Oct. 10, 1950 2,570,915 Buck Oct. 9, 1951 

